The present invention relates to an actuator, having a motor and an actuator component operable by the motor, having a movable gear component with at least one first and one second limit stop component, and at least one limit stop element with an inner and an outer reference plane, serving as limit stop of the limit stop component of the gear component. Furthermore, the invention relates to the use of an actuator for the headlamp leveling of a headlamp.
The increasing demand for more operating comfort and more safety lead to the development of more and more intelligent and therefore more complex systems. In an automobile, these systems are for example climate control, breaking and locking systems but also headlamp systems. Reliable actuators are required for the execution of the functions of the respective systems. In the course of time the demands on actuators have risen considerably. The functions of the actuators are becoming more complex, the demands on the reliability of the actuators are increasing and the function of the actuators must be guaranteed of an ever extending product life. The respective actuators are usually high-performance designs adapted to a special place of installation, i.e. to special systems. Electromechanical and electronic components are integrated in intelligent actuators.
Typical fields of application for such actuators are e.g. locking/unlocking, remote control for tank caps, tail gates, storage compartments or headlamp leveling. Safe driving in the dark is only possible with headlamps whose angle of inclination is always correctly adjusted. Only then is the road optimally illuminated and the oncoming traffic is not dazzled. With the manual headlamp leveling customary in today's motor vehicles the driver has the possibility to adapt the inclination of the headlamp to the current load condition by means of a switch on the dashboard. Modern headlamp leveling systems automatically adapt the angle of inclination of the headlamp to that of the vehicle body without any involvement of the driver. Here a differentiation is often made between two systems. Static headlamp leveling corrects changes in the angle of inclination on the basis of load conditions of the motor vehicle. In addition to that, dynamic headlamp leveling also reacts to changes in the angle of inclination caused by braking and acceleration of the motor vehicle.
Systems with special headlamp leveling power lighting modules, such as e.g. AFS systems (AFS=adaptive front lighting system), represent a photometric innovation in which the light distribution is adapted to the driving situation, i.e. for driving in the city, on country roads or on motorways in addition to adjusting the light beam to the course of the road.
The actuators required for this purpose execute instructions calculated by a control unit. This means that the actuators transform electric signals from the control unit into physical variables.
Future light-based driver assistance systems (LBAS) will require a high degree of positioning accuracy of the lighting function over the entire temperature range. Current actuators are made from a thermoplastic material, such as e.g. PBT. This means, a substantial part of the component parts of such actuators is made from thermoplastic material, such as PBT. Actuators are, however, sometimes exposed to extreme thermal conditions, in a motor vehicle, for example. Temperature changes ranging from −40° C. to more than +120° C. are possible in automotive headlamps. Furthermore, the requirements relating to thermal resistance of headlamps and therefore also of the actuators connected with the headlamps, for example 4 h at 120° C., are very high. These temperature changes and high thermal resistance requirements lead to variations in the material expansion of the components of a system, such as a headlamp system. For a headlamp leveling actuator of a headlamp system this means that reference planes of the actuator are lost for safe and dazzle-free operation due to poor thermal stability of the thermoplastic material of the actuator, caused for example by a large coefficient of thermal expansion. As misadjustment of a headlamp during driving must be avoided at all cost because of the danger of dazzling the oncoming traffic, the actuators are referenced again with every start of operation. This shall ensure the exact positioning of the actuator and therefore of the actuator component of the actuator in the headlamp. A headlamp leveling actuator, and particularly a part of the actuator component of the actuator can, depending on the installation position in the headlamp, drive into a number of different limit stop components of the actuator, e.g. a housing cover, for the execution of the referencing process. After the start of the referencing process, the actuator component of the actuator runs hard against the respective limit stop component with an excess number of steps.
A disadvantage of the currently known actuators is that the involved plastic parts do not meet the exacting requirements with regard to temperature resistance and accuracy. Plastic deformation leads to a loss in accuracy of the actuator.